. >> i have strengthened medicare. we've added years to the life of medicare. we did it by getting rid of taxpayer subsidies to insurance companies that weren't making people healthier. >> reporter: by 2014 the law requires everyone to have health insurance. whether they purchase it themselves, or through their employers. and insurers can't deny you if you have a pre-existing condition. or increase your rates. in hopes of covering more people the law planned to expand medicaid to the states with the aim of covering 17 million more people. but the supreme court ruled in june that it was up to each state to decide whether to expand coverage. the law has become a cornerstone of the obama campaign. >> i refuse to eliminate health insurance for millions of americans who are poor and elderly or disabled all so those with the most can pay less. >> reporter: but romney says the affordable care act is unaffordable. >> we know that health care is too expensive. obama care doesn't make it less expensive. >> reporter: romney and his running mate paul ryan propose to cap ma